The invention relates to the general technical field of assembling elements together.
In particular, it relates to an assembly method, an assembly installation, a device assembled thereby, and a unit including the device.
The term xe2x80x9cassemblyxe2x80x9d is used herein to mean any operation whereby at least two hard and brittle elements are secured to each other, and also to at least one deformable element disposed between the two hard and brittle elements, rigidly and in irreversible manner.
The term xe2x80x9cirreversiblexe2x80x9d means that separating the elements will spoil them.
Such assembly is common in numerous technical fields, regardless of the structure and/or the composition of the materials and/or the final purpose of the elements.
Such assemblies are desirable in numerous technical fields such as building and public works, furniture, and mechanical engineering, in particular.
For greater simplicity, the invention is described in the field of glazing. The scope of the invention is not limited in any way to glazing, which is merely the context in which the invention originated.
Likewise, the term xe2x80x9cenvelope elementxe2x80x9d for designating the elements that are hard and brittle is employed herein for the purpose of simplicity. It implies no limitation as to the number and/or disposition of such elements.
A technical problem solved by the invention is described with reference to an example concerning laminated glazing.
The following documents are mentioned in this field.
Document DE-A-38 37 701 describes a window provided with holes into which adhesive is inserted for bonding purposes.
Document GB-A-2 024 297 describes a window with a channel section rail onto which fixing bolts are welded.
Document U.S. Pat. No. 4,307,551 describes glass plates for covering a wall, and including section member rails stuck in the region of the edges.
Document EP-A-344 486 describes a thick glass plate for covering purposes, with sheet metal stuck thereto.
In laminated glazing, the envelope elements are generally made of glass, synthetic material, or the like. The deformable element(s) is/are generally made of thermoplastic synthetic material in the form of laminations.
The elements are said to be xe2x80x9cdeformablexe2x80x9d since they are suitable for being deformed plastically and irreversibly, commonly known as xe2x80x9ccreepxe2x80x9d.
A rise in temperature, e.g. under the effect of the sun, increases creep.
In particular, under certain conditions of temperature and/or stress, these elements are deformed because of their low resilience. Thus, they do not return to their original shape once the conditions have gone.
For example, the application of stress on laminated glazing, e.g. in the form of compression for holding the glazing in position, often gives rise to creep.
This causes mechanical damage, and spoils the waterproofing of the glazing and/or the unit in which it is integrated.
The mechanical damage appears as a change in the shape of the glazing (delamination, thickness, etc.).
When that happens, the glazing is no longer properly held or driven. In particular, the connection between the glazing and the holding and/or drive means is degraded (backlash, vibration, jamming, etc.), and may even be broken.
At present, industrial solutions are unsatisfactory, in particular because of cost.
To secure the glazing to its holding and/or drive means, it is common practice to provide it with discontinuities that open out to two opposite faces in the main direction of the stresses. These discontinuities are generally ports, holes, or openings.
This weakness the glazing and increases its cost. Also, the means secured to the glazing are then heavy, whereas, on the contrary, industry is looking for ways of reducing weight.
The same drawback of weight is to be found with means secured by clamping the glazing by means of a yoke.
A channel section insert, e.g. made of rubber or the like, generally engages the edge of the glazing and is rigidly connected to the yoke. The size, the reliability, and the simplicity of the unit including the glazing all suffer therefrom.
These drawbacks present further difficulties when faced with increasing requirements of the industry concerning soundproofing, reduction in weight and size, and concerning safety and reliability (ability of the assembly to withstand shock and conditions of heat or humidity, etc.).
It is also appropriate to restrict or even eliminate manufacturing rejects due to delamination, defects, or breakage, e.g. due to final assembly in an autoclave (often at 1.2 MPa and at 145xc2x0 C. for more than 1 hour).
Delamination can also occur during assembly or during the aging cycle, and can escape attention during assembly, which is one of the causes of such elamination.
The above problems are described in the context of aminated glazing, but they also occur in numerous other mechanical fields.
There is a common need to apply compression stresses from the outside on a device having an envelope which is hard and brittle and a core which is flexible. A term sometimes used is xe2x80x9clow resiliencexe2x80x9d.
This applies to a panel or part provided with hard outer layers (cellulose material, synthetic material, metal, or porcelain or plaster) against which stressed need to be applied, and an internal part that is deformable, such as insulating foam, a sealing film, a biological barrier, or the like.
Such panels or parts are often to be found in furniture, public works, building, mechanical engineering, etc.
There therefore exists considerable demand to solve the problems and drawbacks mentioned.
To this end, the invention provides a method of assembling at least two envelope elements and at least one deformable element between the two envelope elements to secure these elements together rigidly in irreversible manner, the assembled-together elements being designed to be subjected to compression stresses in a direction that intersects, or is even substantially perpendicular to, at least one assembly surface.
This method comprises the following combination of steps:
placing at least a first envelope element in an assembly position with at least a first assembly surface accessible;
placing at least a deformable element with a first assembly surface facing the first assembly surface and with an intermediate second assembly surface that is accessible, said deformable element being provided with at least one compression pad and/or with at least one void formed therein;
optionally placing at least one separate compression pad in said void, facing the assembly surface of the first envelope element;
placing at least a second envelope element with at least one assembly surface facing at least an assembly surface of a deformable element and/or at least one compression pad; and
performing bonding treatment such that at least one compression pad has its first assembly surface in contact with the assembly surface of the first envelope element, and that a second assembly surface of a compression pad is in contact with the assembly surface of the second envelope element.
This provides a continuous bridge with one or more adjacent pads between the envelope elements, with the bridge being strong in compression and capable of absorbing stress without harming the assembly.
In a particular implementation, the bonding treatment step includes a mechanical transformation operation such as deformation, e.g. by pressing at least one pad and/or a physical transformation such as depressurizing or putting under a vacuum.
In an implementation, the bonding treatment step includes a chemical transformation operation such as polymerization, solidification, and/or drying.
In an implementation, the method provides for the bonding treatment step to include a heating operation e.g. in a bag oven and/or a stove.
According to a characteristic, the method includes a plurality of steps consisting in:
placing at least one deformable element with a first assembly surface facing a first or a second assembly surface; and
optionally placing in a void formed therein at least one separate compression pad.
The invention also provides an installation for assembling together at least two envelope elements with at least one deformable element between the two envelope elements to secure the elements together rigidly in irreversible manner using the above-specified method.
An embodiment provides means selected from: a clean room and/or a conveyor system and/or a heater system, such as a bag oven, and/or a wheel pressing system.
The installation is provided with programmable means such as a detector or a controller, for monitoring the extent to which steps or operations have been accomplished and/or suitable for performing such steps or operations automatically, at least in part.
The invention also provides a device that is designed to be subjected to compression stress, and including at least two envelope elements and at least one deformable element between the two envelope elements, in which the elements are secured together rigidly in irreversible manner.
By way of example, the elements may be assembled together using the above-mentioned method and/or by means of an installation as described above.
In the device, at least one compression pad disposed between the envelope elements is made of a material whose hardness is substantially less than that of the envelope elements with which it is in contact and greater than that of the deformable element, at least at the bonding treatment temperature. The Vickers or Brinell number of the pad is about 600 to 800, for example.
In an embodiment, at least one compression pad comprises a material selected from: synthetic material such as aramid and/or polyvinyl butyral, and/or glass, and/or a metal such as lead and/or tin, said material being optionally a fiber material and, for example, is bonded to the deformable element by stitching.
According to a characteristic, at least one compression pad and/or one deformable element comprises a portion that is opaque and/or translucent and/or tinted.
An example of the device provides for at least a compression pad and/or a deformable element to be of a size in the intended compression stress direction that is substantially equal to the distance between the assembly surfaces facing it, prior to the bonding treatment step, said size being equal to the distance in the final device.
According to a characteristic, at least a compression pad and/or a deformable element and/or an envelope element is substantially in the form of a lamination, e.g. plane, bulging, or complex.
It is desirable to give the pad a shape that avoids xe2x80x9cwoundingxe2x80x9d the envelope element during assembly.
In an embodiment, at least a compression pad and/or an envelope element, or the device does not have any discontinuity opening out to the two opposite assembly surfaces in the direction of the expected stresses, e.g. a port, hole, or opening.
A characteristic provides for at least one envelope element to comprise a transparent material such as glass or a synthetic material such as polyethylene or the like, the device constituting, for example, laminated glazing.
Another characteristic provides for at least one compression pad to be located in a compression zone and/or to define a pattern, in the assembly plane and/or in cross-section, the pattern being constituted by a polyhedron, lines, or circles.
By way of example, an embodiment of the device comprises, between two elements, at least one fluid and/or film adhesive that is optionally thermosetting.
The invention also provides a unit including a device as mentioned above.
The unit comprises holding and/or drive means, e.g. that operate by clamping, which co-operate with the device in register with at least one compression pad, said means contributing to securing the device to the unit, and optionally to driving the device between two positions.
In an embodiment, the unit includes a passage, optionally provided with sealing means, with all of the compression pads of the device being located on one side only of the passage regardless of the position of the device, the unit constituting, for example, a vehicle bodywork component such as a door, and the device constituting laminated glazing.